Remove two unused db.api methods

Remove two methods from the db API that are no longer used.  These
methods were deprecated when the VolumeMapping object was created,
which doesn't use them.  The relevant code has been converted to use
the VolumeMapping object, so these can now be removed.

Change-Id: I8c230d994a108c9f4c1ee7e112178b852520cb3e
Merge "Remove two unused db.api methods"